1. Field of Invention
The present invention relates, for example, to a light source unit including an arc tube having a light emitting section in which discharging emission between electrodes is carried out, a first reflecting mirror to emit a luminous flux radiated from the arc tube in a certain uniform direction, and a second reflecting mirror provided on the opposite side of the light emitting section from the first reflecting mirror, an illuminating optical device, a projector, and a method of manufacturing the light source unit.
2. Description of Related Art
In the related art, for example, in an illuminating device provided with an arc tube having a light emitting section and a first reflecting mirror injecting a luminous flux radiated from the light emitting section in a certain uniform direction, a second reflecting mirror is provided at the position opposite side of the arc tube from the first reflecting mirror so that light, which has been radiated from the arc tube but has become stray light and hence has not been used, can be used efficiently, as shown in related art document JP-A-8-31382.
In such an illuminating device, a high degree of accuracy is required to adjust the relative position among the arc tube, the first reflecting mirror and the second reflecting mirror in order to obtain the brightness of a luminous flux emitted from the illuminating device, and the position of a focusing point at desired values.